Vulcanizing seal



Aug l, 1950 H. E. THOMPSON 2,517,054

vULcANIzING SEAL Filed June 17, 1946 /ITTORNE YJ Patented Aug. 1, 1950 UNITED STATES PATENT OFFICE VULCANZING SEAL ration ofDelaware Application June 1.7., 1946, .Serial No. 67753.47

2 Claims. l

This invention. relates to continuous vulcanization of rubber-covered Wire and, more particul'arly,A to a seal adapted to provide substantially pressure-tight closure of the end of a continuous vulcanizing chamber through which a rubbercovered Wire is moved. The vulcanizing` seal of the invention provides such` closure of a vul canizing chamber While permitting substantially non-distortional movement of the covered. Wire through the seal.

In the production of rubber-covered. Wire, the Wire is passed through an extrusion die wherein a covering of plastic rubber is applied about the wire. In order to vulcanize this rubber covering, the wire leaving the extrusion die is passed through an elongated vulcanizing chamber containing a vulcanizing medium (steam) under super-atmospheric pressure. The maintenance of high pressure steam Withinthe, vulcanizing. chamber requires the use of pressure seals. at each` end oi the vulcanizing chamber.. Not onlyI must. these seals be capable of. maintaining asteam pressure of', say. two hundred poundsper squareinch in. the

vulcanizing chamber, but they must be such. as y to avoid deleterious distortion` or other damage tothe rubber covering,r about the Wire. Numerous seals havebeen proposed and used heretofore for this. purpose, but` seals which` have been capable of. maintaining the desired steam pressure Withinthe Vulcanizing chamber Withoutexcessire loss of steam have tended t0` damage` the rubber covering on the wird, and those. seals which have not damaged the covering have not.. generally beencapable of. maintaining the` desired. steam pressure without. considerable loss of steam through the` seals. Furthermore, these and other seals, pro-- posed and used heretofore require considerable maintenance and frequent replacement of` parts.

The present invention contemplates a` novel seal. adapted to be used at, either or both ends of a continuous vulcanizing. chamber for the treatment of rubber-covered vvire.` The novel seal of' this invention provides a closure of the. desited, characteristics without requiring the use` of any extraneous medium or agentV under high pressure to counteract the tendency of the high pressure vulcanizing medium to escape.

The vulcanizing chamber seal oi the: present invention comprises a plurality ofA steam.. condensing chambers serially arranged within; the end of the vulcanizing chamber. The` condensing chambers are separated from one another by a partition provided with an orifice oi sufficient size to permit substantially non-distortional move.- ment` of the Wire therethrough.` The orifice in.

each. partition is also sufficiently small to prevent unhindered escape of the vulcanizing medium therethrough. Cooling means are provided to` effect heat-transfer cooling of steam in each of the condensing chambers. in a particularly advantageous embodiment of the invention, the cooling means comprises a Water jacket surrounding the end of the vulcanizing chamber provided with the steamcondensing chambers. The crosssectional area of the clearance space between the Wire and the orice in each partition is preferably less than about ten percent of the internal cross-sectional area of the steam condensing chambers. This, arrangement provides a series ot zones between the spaced partitions Withinthe end of the vulcanizing chamber containing the steamy under successively decreasing pressures, thusv minimizing theescape of steam through the oriiices which are nevertheless of suicient sizeto permit relatively free movementof the rubber-- covered wire therethrough. Thus, the inventioncontemplates a method of sealing the end of a continuous vulcanizing chamber of the type described hereinbefore by establishing adjacent the end of` thel steam vulcanizing chamber and about` the wire moving therethrough a series of Zones ci thevulcanizing steam under successively decreasing pressures, these zones being cooled by means ot heat transfer without the need of passing a cooling. medium in direct contact with the steam.

These and other novel features of the invention Will be` further understood from the iollowing description taken in conjunction with the accompanying drawing, in which the single iigure shows the novel seal of the invention applied at. both ends of a continuous vulcanizing chamber..

The` Wire 5 to be covered with rubber is passed through an extrusion die E to which. rubber under pressure is supplied, through a delivery line l. The, wire. leaving the extrusion die 6 is thus covered with plastic rubber which must be vulcanized before it. is, of practical use.

The rubber-covered Wire leaving the extrusion die` Si passes through an entry seal it of an elongated tnbular chamber lll filled with high pressure, steam. adapted` to. effect vulcanizing of the rubber covering during passage oi the Wire throughout the length of the chamber. The entry sealA 8 may be. directly connected to the extrusion die chamber as. shown` in the drawing, or it may l be physically separated therefrom in order to permit visual inspection of` the rubber-covered Wire.

as thevvire. leaves the die. The vulcanizing steam,

under super-atmospheric pressure of,` say, about two hundred pounds per square inch, is supplied through a pressure line I I communicating with the Vulcanizing chamber lil. The vulcanized wire is withdrawn from the vulcanizing chamber through an exit seal I2 at the discharge end of the vulcanizing chamber.

The vulcanizing chamber, as shown in the drawing, is provided with a seal in accordance with the invention at both ends. novel seal may be used at only the discharge end of the vulcanizing chamber, relying upon some other conventional seal at the entrance to the vulcanizing chamber where the difficulty of sealing is lessened by the sealing effect of the extrusion die 6.

The vulcanizing chamber seal, in accordance with the invention, may be provided within and about the end portion of the vulcanizing charnber itself or it may embody a separate chamber portion which is secured to the vulcanizing chamber. Thus, the end portion or" thel vulm canizing chamber referred to herein and in the claims is intended to include the actual end portion of the vulcanizing chamber as well as a separate end portion secured thereto. portion It of the vulcanizing chamber is pro-x vided in accordance lwith the invention with aplurality of partitions Iii serially positioned in spaced relationship therewi'thin. The partitions may be formed integrally with the rest oi the chamber i3 or may comprise plugs or the like inserted within the chamber and appropriately secured in proper position. The plurality of spaced partitions ifi separate the end portion of the vulcanizing chamber into a plurality of zones or steam condensing chambers between which communication is provided only by means of longitudinal orifices I5 provided through each partition. The orifices I 5 are of suflicient size to permit substantially non-distortional movement of the wire therethrough. That is, the orifices I5 are of such size that the rubber-covered wire may pass therethrough without sumcient frictional contact or abrasion to damage or in any way adversely aiect the quality of continuity of the rubber covering. However, the size oi the Orices is made suiliciently small to prevent unhindered escape of the steam between the interior surface of the orice and the surface of the covered wire passing through the orifice. Thus, each of the orifices i5 is of sulcient size to act somewhat as a reducing valve, the space between the surface of the covered wire and the interior ofeach. oriiice providing a restricted opening through which steam, and water resulting from condensation of the steam, may pass into the open zone or space between adjacent partitions. I have found it particularly advantageous to maintain the cross-sectional area of the free space between the wire and the interior surface of the orifice less than about ten per, cent of the internal cross-sectional area of the free space zone between adjacent partitions. In this manner, the high pressure steam within the vulcanizing chamber IU escapes through the small space between the wire and the orice of that partition which is positioned immediately adjacent the end of the vulcanizing zone of the chamber I This restricted escape of high pressure steam results in the establishment of a zone of somewhat reduced pressure steam between this partition and the second (next) partition. Escape of this reduced-pressure steam through the orice I5 in the second partition further reduces the steam pressure within the second However; myVU The end free space zone between the second and third partition, Thus, a decreasing pressure gradient is established in the successive zones extending from the high pressure vulcanizing zone within the chamber Ii) toward the extreme end of the chamber. The decreasing pressure serves to cool the steam so that, in effect, the zones or spaces between partitions I comprise steam `-condensing chambers The extent of pressure reduction` from one Zone or condensing chamber to the next in the seal is enhanced in accordance with the invention by a cooling jacket l5 surrounding that end portion of the vulcanizing chamber which is provided internally with the steam condensing chambers. Any suitable cooling medium such as water may be used, the cooling medium being circulated through appropriate delivery and discharge openings. The cooling effect provided by the cooling jacket augments 'thefcooling effect provided by expansion of relatively high pressure steam through the restricted space partition orifice into the relatively large free space between each partition and the next adjacent partition.. As a result, the steam is largely condensed tok water before it reaches the end oi the seal so that in at least one or more of the last partitions in the seal the free space between the wire and the interior surface of the orifice I5 may be iilled with water comprising the condensed steam. The thickness of the partition (that is, the

length oi the longitudinal orifice it in the partition) thus serves to increase the resistance to` flow of wat-er through the restricted space be-- tween the wire and the interior surface of the orice It so as to enhance the pressure drop, between adjacent Zones on opposite sides of each partition without requiring rm physical contact between the covering of the wire and the interior of the orifice. The relatively high velocity of this water (condensed steam) iiowing through the small free space in the orifice I5 in one partition and discharging into the relatively large volume of the space zone between this partition and the next adjacent partition creates ar substantial pressure drop in accordance withv Bernoullis theorem. The combined effects of the spacing between the plurality of partitions,

the thickness of the partitions, `and the free but limited space between the surface of the covered l wire and the interior surface of each partition` provided which communicates advantageously with the extreme end portion or the chamber 'A The end of the exit portion of the seal may be provided with advantage with an additional partition I4 simibeyond the cooling jacket It.

lar to the others used .in the seal and held in place by a collar It threaded over this exit end v of the seal chamber.

Seals, in accordance with the invention, provided at both ends of the vulcanizing chamber may be provided with the same number or" steam condensing chambers or a different number of such chambers. In general, a larger number of condensing chambers is required in the exit sealf than is required in an entry seal attached to the extrusion die 6 due to the assisting sealing effect of the extrusion die adjacent the entry end of the chamber. The number of steam condensing chambers used in seals in accordance with my invention will depend upon the amount of steam pressure maintained within the vulcanizing chamber and the amount of free space or tolerance between the surface of the rubber-covered wire and the interior surface of the partition oriiices l5. By Way of illustration, and not as any limitation to th-e invention, I have found that with a vulcanizing steam `pressure of two hundred pounds per square inch and with the crosssectional area of free space between the surface of the covered wire and the interior of the partition orifices I5 limited to not more than ten percent of the internal cross-sectional area of the steam condensing chambers, eiective sealing may be provided at the exit end of the Vulcania ing chamber with four or ve condensing chamm bers Within the cooling-jacketed end portion of the vulcanizing chamber.

I claim:

1. A seal for the end of a continuous vulcanizing chamber through which a rubber-covered wire is passed continuously in contact with a vulcanizing atmosphere of high pressure steam maintained Within the chamber, said seal comprising a plurality of steam condensing chambers serially arranged within the end of the vulcanizing chamber, a cooling jacket surrounding said steam condensing chambers, each of the chamu bers being separated from its adjoining chamber by a partition provided with an oriiice of suiiicient size to permit movement of the wire therethrough free from distortion of its rubber covering, said partitions being of such thickness that said oriiice has the form of an elongated tube which, when occupied by said wire. provides an elongated annulus about the wire having a crosssectional area less than about ten percent of the internal cross-sectional area of said steam condensing chambers, whereby said annulus in each partition constitutes a reducing valve adapted to materially reduce the pressure of the steam in each of the successive chambers in a direction proceeding from the vulcanizing chamber to the end of the seal and said annulus further contributes by its considerable length relative to its cross-sectional area to pressure reduction between adjoining steam condensing chambers by the frictonal resistance to the flow of steam and condensed steam therethrough.

2. A seal for the end of a continuous vulcanizing chamber through which a rubber-covered Wire is passed continuously in contact with a vulcanizing atmosphere of high pressure steam maintained within the chamber, said seal comprising a plurality of steam condensing chambers serially arranged within the end of the vulcanizing chamber, a cooling jacket surrounding said steam condensing chambers, each of the chambers being separated from its adjoining chamber by a partition provided with an orifice of surdcient size to permit movement of the wire therethrough free from distortion of its rubber covering, said partitions being of such thickness that said orifice has the form of an elongated tube which, when occupied by said wire, provides an elongated annulus about the wire constituting the sole means for the removal of steam and condensate from each chamber to the last chamber of the series, said annulus having a crosssectional area less than about ten percent of the` internal cross-sectional area of said steam condensing chambers, whereby said annulus in each partition constitutes a reducing valve adapted to materially reduce the pressure of the steam in each of the successive chambers in a direction proceeding from the vulcanizing chamber to the end of the seal and said annulus further contributes by its considerable length relative to its cross-sectional area to pressure reduction between adjoining steam condensing chambers by the frictional resistance to the ow of steam and condensed steam therethrough, and a drain for removing condensate from the last chamber of the series.

HENRY E. THOMPSON.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date 722,219 Fielden Mar. 15, 1903 1,795,311 Meyer Mar. 10, 1931 2,069,087 Forstrom et al Jan. 26, 1937 2,230,283 Boggs Feb. 4, 1941 

